tree-wide: make parse_ifindex simply return the index

We don't need a seperate output parameter that is of type int.  glibc() says
that the type is "unsigned", but the kernel thinks it's "int".  And the
"alternative names" interface also uses ints. So let's standarize on ints,
since it's clearly not realisitic to have interface numbers in the upper half
of unsigned int range.

src/basic/in-addr-util.c

@@ -439,48 +439,38 @@ int in_addr_from_string_auto(const char *s, int *ret_family, union in_addr_union
         return -EINVAL;
 }
 
-int in_addr_ifindex_from_string_auto(const char *s, int *family, union in_addr_union *ret, int *ifindex) {
+int in_addr_ifindex_from_string_auto(const char *s, int *family, union in_addr_union *ret_addr, int *ret_ifindex) {
         _cleanup_free_ char *buf = NULL;
         const char *suffix;
-        int r, ifi = 0;
+        int r, ifindex = 0;
 
         assert(s);
         assert(family);
-        assert(ret);
+        assert(ret_addr);
 
         /* Similar to in_addr_from_string_auto() but also parses an optionally appended IPv6 zone suffix ("scope id")
          * if one is found. */
 
         suffix = strchr(s, '%');
         if (suffix) {
-
-                if (ifindex) {
+                if (ret_ifindex) {
                         /* If we shall return the interface index, try to parse it */
-                        r = parse_ifindex(suffix + 1, &ifi);
-                        if (r < 0) {
-                                unsigned u;
-
-                                u = if_nametoindex(suffix + 1);
-                                if (u <= 0)
-                                        return -errno;
-
-                                ifi = (int) u;
-                        }
+                        ifindex = parse_ifindex_or_ifname(suffix + 1);
+                        if (ifindex < 0)
+                                return ifindex;
                 }
 
-                buf = strndup(s, suffix - s);
+                s = buf = strndup(s, suffix - s);
                 if (!buf)
                         return -ENOMEM;
-
-                s = buf;
         }
 
-        r = in_addr_from_string_auto(s, family, ret);
+        r = in_addr_from_string_auto(s, family, ret_addr);
         if (r < 0)
                 return r;
 
-        if (ifindex)
-                *ifindex = ifi;
+        if (ret_ifindex)
+                *ret_ifindex = ifindex;
 
         return r;
 }

src/basic/parse-util.c

@@ -79,11 +79,10 @@ int parse_mode(const char *s, mode_t *ret) {
         return 0;
 }
 
-int parse_ifindex(const char *s, int *ret) {
+int parse_ifindex(const char *s) {
         int ifi, r;
 
         assert(s);
-        assert(ret);
 
         r = safe_atoi(s, &ifi);
         if (r < 0)
@@ -91,26 +90,24 @@ int parse_ifindex(const char *s, int *ret) {
         if (ifi <= 0)
                 return -EINVAL;
 
-        *ret = ifi;
-        return 0;
+        return ifi;
 }
 
-int parse_ifindex_or_ifname(const char *s, int *ret) {
+int parse_ifindex_or_ifname(const char *s) {
         int r;
 
         assert(s);
-        assert(ret);
 
-        r = parse_ifindex(s, ret);
-        if (r >= 0)
+        r = parse_ifindex(s);
+        if (r > 0)
                 return r;
+        assert(r < 0);
 
         r = (int) if_nametoindex(s);
         if (r <= 0)
                 return -errno;
 
-        *ret = r;
-        return 0;
+        return r;
 }
 
 int parse_mtu(int family, const char *s, uint32_t *ret) {

src/basic/parse-util.h

@@ -13,8 +13,8 @@ int parse_boolean(const char *v) _pure_;
 int parse_dev(const char *s, dev_t *ret);
 int parse_pid(const char *s, pid_t* ret_pid);
 int parse_mode(const char *s, mode_t *ret);
-int parse_ifindex(const char *s, int *ret);
-int parse_ifindex_or_ifname(const char *s, int *ret);
+int parse_ifindex(const char *s);
+int parse_ifindex_or_ifname(const char *s);
 int parse_mtu(int family, const char *s, uint32_t *ret);
 
 int parse_size(const char *t, uint64_t base, uint64_t *size);